Fluid cooled elements for radio circuit



May 30, 1939;

G. H. WILLIAMS FLUID COOLED ELEMENTS FOR RADIO CIRCUIT Flled Dec. 15, 1936 2 sheets sheet l 0/1 LEVAZ 0/1. LEVEL Gttorneg May 30, 1939..

G. H. WILLIAMS FLUID COOLED ELEMENTS FOR RADIO CIRCUIT Filed Dec. 15, 1936 2 Sheets-Sheet 2 0/4 LEVEL Zhwentor (Ittorneg Patented May 30, 1939 UNITED STATES PATENT OFFICE FLUID COOLED ELENIENTS FOR. RADIO CIRCUIT tion of Delaware Application December 15, 1936, Serial No. 115,896

6 Claims.

My invention relates to radio circuits and more specifically to high-power circuits comprised of elements which include fluid-cooling means.

In its broader aspects, my invention includes a high-power radio transmission circuit employing water-cooled thermionic tubes, water-cooled inductors, and an oil-water cooled capacitor. A single source of water is circulated through the several elements. The capacitor is cooled by both oil and water circulation. In high-power installations, it has been customary to use series-paral lel combinations of mica-insulated capacitors. While such capacitors safely stand the impressed voltages, the power losses cause the generation of excessive heat, which may be controlled to a limited extent by immersing the capacitors in an oil bath. The oil bath is not suflicient and capacitors of large physical dimensions are required to handle the power without excessive heat losses.

anodes of the associated tubes may be circulated through the capacitor case whereby the heat losseslare greatly reduced and capacitors of smaller physical dimensions may be used with saving in space and material.

One of the objects of my invention is to provide means for fluid-cooling the tubes, inductors and capacitors of a high-power radio circuit.

7 Another object is to provide means for watercooling an oil-immersed capacitor.

A further object is to provide means for employing a portion of the water which is used to cool the anodes of a thermionic tube for cooling a capacitor.

A still further object is to provide a single fluid circulating path for the tube, radio frequency choke, inductor and capacitor of a radio circuit.

My invention may be best understood by referring to the accompanying drawings in which Fig. 1 is a schematic circuit diagram of a radio circuit,

Figs. 2 and 3 are views, partly in section, of embodiments of my invention,

Figs. 4 and 5 are respectively a sectional view along the line IV-IV and an elevational view, partly in section, of one embodiment of the fluidcooled capacitor of my invention.

Referring to Fig. 1, a source I of high frequency currents is connected in push-pull relation to the grid electrodes of thermionic tubes 3, 5. The anodes of these tubes are connected through radio frequency chokes I, 9 to a tuned. circuit The tuned circuit II is comprised of a center-tapped inductor l3, and capacitors |5, H. The center top of the inductor I3 is connected to the positive I have found that water employed in cooling the terminal of the B supply l9. The negative terminal of the B supply is connected to the cathode.

The foregoing circuit is embodied in the combination of the fluid-cooled elements of Fig. 2 which are arranged as follows: The water-jacketed anodes 2| of tubes 23 are connected by suitable inlet 25 and outlet 21 pipes, of copper or the like, which are each wound in a bifilar helix or spiral to form radio frequency chokes 28. The chokes are connected through coupling Ts 29, 3| to inductors 33, which are also metal pipes wound in bifilar helix or spiral form. The center of the inductors 33 is jointed by T couplings 35 which are connected to a coil of porcelain or other insulating piping 31. The two inductor windings form a single inductor for the resonant circuit. The pipes 31 are of suflicient length to prevent direct current losses from the B supply. The porcelain pipes are connected to the intake and outlet of the cooling fluid supply, which is not shown.

The T couplings 29, 3| between the chokes 28 and inductors 33 are respectively connected to the inlet pipe 39 and outlet pipe 4| which are connected to a hollow metal stud 43. One terminal of each of the capacitors, which will be hereinafter described, is formed by the hollow metal stud 43. The other terminal of each of the capacitors is the casing 45. The casings are connected by a lead 41.

In Fig. 3 the inlets of the anode jackets 5| are connected to helical-wound metal pipes 53 which are radio frequency choke coils. The remote terminals of the choke coil pipes are connected to the outlet pipes 55 of the capacitor studs 51. The inductors are formed of helical-wound pipes 59, which begin with the inlet pipes 6| in the studs 51 and terminate in a T coupling 62, which is in turn connected to the porcelain helix 63. The helix 63 forms the cooling fluid inlet. The cooling fluid outlet is a helical porcelain pipe 65, which is connected to the anode jacket 5| of each vacuum tube. If the required volume of the cooling fluid exceeds the fluid-circulating capacity of the stud 51, a by-pass valve 61 may be connected between the inlet El and outlet 55 pipes in the stud 51.

Referring to Figs. 4. and 5, which are respectively a sectional view and an elevational view, partly in section, of the capacitor which is embodied in my invention, an insulated dome H is suitably mounted on a metal casing 13. A hollow metal stud I5 is secured to the dome and insulated thereby with respect to the casing 13. The stud includes an inlet pipe 11, which preferably extends to nearly the bottom of the stud, and

an outlet pipe 79, which extends to just Within the hollow portion of the stud.

Capacitor stacks 8i are placed on the opposite sides of the stud l5 and spaced from the bottom of the casing 13. These capacitors 8| are clamped in position by headless screws 83, which are threaded through flats on the diagonal corners of the casing 73. The out-portions of the screw holes include cap screws 85 and suitable washers, which make the case fluid-tight. The casing is preferably filled with oil to the level indicated. The oil not only insulates but cools the capacitor stacks.

Each of the capacitor stacks 8| is comprised of alternate layers of mica and metal foil. The metal coil is arranged in series-parallel connection to thereby form the armatures of the capacitor. The outer plate or foil of each stack is the terminal of each respective stack. A suitable metal plate 81 is included between each screw 83 and the associated stack to prevent injuring the stack when pressure is applied.

The intimate contact between the stud 15 and the capacitors 8| form not only a good electrical connection but also an excellent path for conducting heat from the several stacks. The Water or other cooling fluid circulating within the stud readily removes the heat from the stacks and the oil. The cooling effect of the stud is applied to effect a circulation of the oil about the stacks and thereby effect further cooling. In some installations, the oil bath may be omitted but I prefer to use the oil for its combined cooling and insulating properties.

In the foregoing capacitor, the several stacks are connected in parallel, the stud acting as one terminal and the casing as the other. The several stacks are selected to provide the proper capacitance so that, with a selected value of inductance, the circuit will resonate at the desired frequency. It should be understood that the inductor may be adjusted to obtain the desired frequency characteristic.

Thus, I have described a radio frequency circuit which is comprised of elements with fluidcooling means included therein. These elements are arranged so that inductors, chokes, tubes and capacitors are cooled by a single fluid circulation. The capacitor is provided with dual-cooling means, namely, an oil bath and a circulating cooling fluid. The cooling stud of the capacitor also forms one terminal of the capacitor. It should be understood that the choke coils are not always necessary but may be employed to eliminate or reduce currents of parasitic frequencies. Likewise, while a single tube and single circuit may be used, I prefer to use a pair of tubes and a push-pull circuit connection.

I claim as my invention:

1. A circuit including in combination a thermionic tube including a fluid-cooled anode, a fluidcooled capacitor, means connecting said anode and said capacitor for electrical currents and for circulation of a cooling fiuid,'a fluid-cooled inductor, including a pair of terminals, a connection from said capacitor to one of said terminals providing a path for electrical currents and for said cooling fluid, and means connecting said capacitor to the remaining terminal of said inductor.

2. A circuit including in combination a pair of thermionic tubes including fluid-cooled anodes, a fluid-cooled capacitor, means connecting said capacitor and said anodes forming an electrical current path and including a path for circulating cooling fluid within said capacitor, a fluid-cooled inductor connected to said capacitor and including connection for said fluid and said electrical current and a connection for supplying direct currents to said anodes.

3. A circuit including in combination a thermionic tube including a jacketed-anode including inlet and outlet fluid circulation connections, a pair of pipes connected thereto, a fluid-cooled capacitor including fluid inlet and outlet connections, means connecting said inlet and outlet connections and said pair of pipes, a fluidcooled inductor comprising a bifilar-wound pair of metallic pipes, means connecting said inductor pipes and said capacitor inlet and outlet, an additional electrical connection from said capacitor to said inductor whereby a circuit is formed, and connections for supplying direct current to said anodes.

4. A circuit including in combination a pair of fluid-cooled thermionic tubes including fluid inlet and outlet connections, a fluid-cooled capacitor including cooling fluid inlet and outlet connections, means connecting said tube and capacitor fluid connections, a fluid-cooled inductor comprising a pair of bifilar helically-wound. pipes, extensions of said pipes connecting said capacitor and said inductor and including both fluid and electrical current paths, and means for impressing direct current on said tubes.

5. A combination of the character of claim 3 in which the electrical current path and fluid path between said anodes and capacitor is a radio frequency choke coil.

6. A combination of the character of claim 4 in which the connection between said tube inlet and outlet connections and said capacitor inlet and outlet connections is a bifilar-wound pair of pipes forming a radio frequency choke coil.

GU'RDON H. WILLIAMS. 

